The current SteamOS is based on Arch Linux, and ./play.it can be used to generate Arch Linux native packages for Rayman Origins: https://www.gog.com/forum/general/linux_playit_weekly_news/post1

I do not own (and do not want to own) a Steam Deck myself, so I don’t know how you are expected to install these packages. On a regular Arch Linux it’s done by running pacman -U package.pkg.tar.zst as root.

There are packages for ./play.it in the AUR, but they don’t seem to be actively maintained. So if these do not provide Rayman Origins support, you can instead install it from git: https://doc.dotslashplay.it/install.git.en.xhtml

The collection adding support for Rayman Origins is my personal collection: https://git.vv221.fr/play.it-vv221/about/